Heat transferrer



June 24, 1930. R. UHDE 1,768,222

HEAT TRANSFERRER v Filed Dec. 19, 1928 2 Sheets-Sheet 1 l v 23 i,

June 24, 1930. R. UHDE I HEAT TRANSFERRER Filed Dec. 19, 1928 2Sheets-Sheet 2 Patented June 24, 1930 UNITED STATES PATENT OFFICE ROBERTUHDE, OI KASSEL-WILHELMSHOHE, GERMANY, ASSIGNOR T0 SCHMIDT SCHEHEISSDAEPF-GESELLSOHAFT MIT BESCHRKNKTER HAFTUNG, OF KASSEL-WILHELMSHOHE, GERMANY, A CORPORATION OF GERMANY HEAT TRANSFERRER.

Application filed December 19, 1928, Serial No. 327,033, and in GermanyDecember 29, 1927.

The invention relates to heattransferrers' and while generallyapplicable is specially designed for the superheating. of steam.

The object of the invention is to construct a heat transferrer, suchthat when applied, e. g., to the superheating of interstage steam, largequantities of steam can be highly superheated without the interstagesuperheater attaining undesirable large dimensions.

In the interstage superheaters of modern steam power plants, thehigh-pressure steam which serves as the heating'medium is led throughheating elements arranged in a container through which passes the steamto be superheated.

According to the present inventi0n, each of a series of like heatingelements arranged side by side consists of two or more tubes connectedin parallel, which for a part of their length. are .formed as helicalcoils and are so assembled that they provide a continuouscoil'sub-divided to correspond with the number of tubes in theindividual elements.

With the new heat transferrer, large quantities of steam can be passedthrough not only the heating elements, but also through the container inwhich they are arranged, and'the latter steam superheated to. a highdegree.

By. reason of the fact that all the heating elements are alike and thateach single heat- .ing element consists of two or more tubes arrangedin'parallel, which together form a continuous coil, a very large heatingsurface is provided and as, in addition, the steam in all the tubespasses over only the same comparatively short length of path, its heatcontent is utilized under the most favourable conditions.

Referring to the accompanying drawings, different forms of the inventionare shown by way of example; 7 I

Figure 1 is a vertical central section of a heat-transferring deviceaccording to my invention, the heating elements, in the central row onlybeing shown for the sake of clearness;

Figure 2 is a horizontal section on line IIII of Fig. 1;'

Figures 3 and 4 show one form of heating element in side elevationsrespectively at right angles to one another; I

Figure 5 shows a modified form of heatingelement in side elevation;

Figure 6 being a cross-section on ,line VI-.VI of Figure 5, and

Figure 7 shows another form of heating element in side elevation.

Referring first to Figures 1 and 2, the

casin 18 containin the heatin elements is closed at the top by a plate,19, and at the bottom .by a plate, 20. To the plate, 19, a

cover, 21, is fastened, provided with chamber, 22, and a branch, 23,leading to that chamber. A similar cover, 24, provided 'with a chamber,25, and a branch, 26, is secured to the bottom of the casing, 18. Theinlet and outlet ends of the heating elements are secured intocorresponding holes in the plates, '19, and 20, and communicate with thechambers, 22, and 25, respectively. The superheating medium entersthrough the branch 23 into the chamber, 22, passes through the heatingelements arranged side by side and leaves the device through chamber,25, and branch, 26. The medium to be superheated enters the casing, 18,through the connection, 27, and leaves the casing through theconnection, 28.

The heating elements. arranged in the casing, 1, are formed partly ashelical coils and partly as straight lengths, assembled as shown by wayof example in the drawings.-

The heating element shown'in Figures 3 and 4 consists of two tubes, 1, 2and 3, 4, connected in parallel. 1

Theone tube as regards its upper half is wound into a helical coil, 1,and at the middle point in the length of the heating element changesover to a straight length of tube 2, by means of a short bend, 5,running inwards to the axis of the element.

The, second tube, 3,, 4, on the contrary, is

straight as regards the 'upper half, 3, of the running outwards from theaxis of the ele- V ment, changes over to a helical coil, 4. In

each case, the straight length of the one tube. lies within the helicalconvolutions of the tube. At the upper and lower ends of the heatingelement, the two tubes are respectively connected by the Y -pieces, 7and 8.

The heating element' shown in Figures 3 and 4 is of somewhat similarconstruction as those arranged in the casing, 18, of Figures 1 and 2.This element is composed of three tubes connected in parallel. The firsttube consists of the upper helically-wound coil, 9, and the straightlength of tube, 10, connected to it below; the second tube comprises thelower coil, 11, and the straight length of tube, 12, connected to itabove; and the third'tube is formed into helically-wound middle part,13, and the straight lengths, 14, 15, connected to it respectivelyaboveand below.

At their upper ends the tubes are connected to the three-limbed Y-piece,16, and at their lower ends to the similar Y-piece, 17, the tubularstems of the Y-piece serving to connect the heating elements to theheader or the like to or from which the heat carrier is led. By the useof such Y-pieces, an undue multiplication of connections is avoided.

The straight lengths of tube in the modifications described are allarranged within the helical convolutions of the heating element. In somecases it might be preferable to have a part of the straight lengthslying outside the convolutions. The heating element of Figure 7, whichis composed of three tubes connected in parallel, has, for example, thestraight lengths of tube 12" and 15' arranged outside the convolutions.

In Figures 1 and 2 the individual heating elements, connected inparallel, are arranged in a circle side by side in the container, 18.Instead of the circular arrangement shown, the heating elements may alsobe disposed in rows, for example, in parallel formation.

The essential requirement is that all the individual heating elementsare connected in parallel so that the highly-superheated steam servingas heat carrier fiows through all'the elements under the sameconditions.

By the sub-division of the like individual heating elements into tubesconnected in parallel and helically wound for only a part of theirlength, the resistance to flow which,

the heat carrierhas to overcome is substantially less than if each tubewere formed as a coil for its whole length; thus, the resistance to flowin the form of the invention shown in Figures 1 and 2 is approximatelyone-half and in the form of the invention shown in Figures 3 and 4,one-third as much as in a single helical coil of the same length.

Transfer of heat, which occurs for the most part in the helical coils,is comparatively large as these coils, notwithstanding theirsub-division, extend continuously over the length of the heatingelement.

In addition, the straight lengths of tube I lying within the helicalconvolutions contribute to the quantity of heat transferred "lengths,and are so assembled that they provide a coil sub-divided to correspondwith the number of tubes of the individual elements.

' 2. In a heat-transferrer of the class described the combination of acasing, an inlet. to and an outlet from said casing, a plural- 1 ityoflike heating elements arranged side by side in said casing and aninlet connection and an outlet connection communicating with saidheating elements, each of which elements consists of two or more tubesarranged in parallel, which are formed partly as helical coils andpartly as straight lengths,

and are so assembled that they provide a U coil sub-divided tocorrespond with the number of tubes of the individual elements, saidstraight lengths of'the tubes passing through the convolutions of thehelical coils.

3. In a heat-transferrer as defined in claim 1, the said tubes formingthe compound coil being connected at each end-of. the'heatingelement toa common Y-piece.

In testimony whereof I have aflixed my signature.

ROBERT UHDE.

lUU

tau

